Generally, various agricultural machines, such as cultivators and tractors, are used to reduce labor costs and to improve production efficiency in the cultivation of crops. However, crops cultured by these machines often require nutrients and/or fertilizers for growth and reproduction. In addition, pesticides are oftentimes sprayed on these crops in order to protect them from pests. To apply these plant nutrients, fertilizers, growth regulators, pesticides, or other agricultural chemicals, liquid in form, on parts of plants or near the root zones of soil surfaces, growers typically use a manually-powered sprayer or applicator, which requires power to be generated by the hands or feet of the laborer, or a power sprayer or injector which utilizes pressure or driving force generated by a compressor, powered by an electric motor or an engine.
The aforementioned manual sprayer is typically used to spray such chemicals in a relatively small cultivating area, while the power sprayer is typically used over a large area where manual spraying may be difficult. Such a power sprayer is capable of continuously spraying agricultural chemicals to a cultivating area by spraying the chemicals through a nozzle, the chemicals being forced through the nozzle by pressure built up by the compressor. In other words, the user holds a nozzle handle that is connected to a hose that is, in turn, connected to a spray material tank and to a compressor, and moves along the crop rows, and sprays or injects chemicals continuously onto a place where the application is needed.
However, by using the power sprayers of this type, a user cannot control the precise amount or volume of liquid fertilizers, nutrients or other agricultural chemicals to be sprayed onto each plant during a continuous or intermittent application. Hence, spraying becomes irregular, resulting in lowered efficiency. Also, a continuous spray from a hand-held nozzle or a tractor-mounted applicator, invariably applies more chemicals than are needed for each plant due to the plant spacing in a row. The irregular and resultant overspraying may cause frequent phytotoxicity to non-target parts of crop plants, leave more harmful pesticide residues on soil surfaces and on crops that, in turn, could harm human beings as well as livestock, pollute the environment, and increase costs of crop production.